[An experimental study on elongation injury of peripheral nerve]

The sciatic nerve of rabbits was indirectly elongated by lengthening the femur to clarify the pathology of elongation injury of the peripheral nerve. Electrophysiologic and morphologic changes and the blood flow in the nerve due to nerve elongation were evaluated in this model. No significant changes were observed when the nerve was elongated by 5.01%. Conduction disturbances, however, developed and the blood flow in the nerve was markedly reduced by sustained 11.8% elongation. In the latter case, the blood-nerve barrier was disrupted after 6-12 hours, endoneurial edema was observed after 48 hours, and extensive degeneration of nerve fibers was noted after 5 days. When the nerve was returned to the original length after 11.8% elongation for 2 hours, degeneration of the nerve fibers followed only partially. These findings suggest that circulatory impairments as well as mechanical damages are closely involved in elongation injury of peripheral nerves. The results also indicate that the duration of elongation plays an important role in determining the severity of elongation injury of peripheral nerves.